When persons experience stress, the pupils of their eyes widen and their rate of blinking increases. Although negotiators rarely interact with others in such proximity that they can see the size of their pupils, they can easily notice increased blinking. This may be due to foreign matter that has entered the eyes of such people, or it may be due to stress associated with deception.

Narrowing/Tightening of Margin of Lips

Stress often causes individuals to briefly narrow and tighten the red margin of their lips just before they speak. Careful observers may be able to see the lips of prospective speakers tighten into a narrow line across their lips just before they utter false statements.

Elevated Voice Pitch

Persons experiencing anxiety frequently raise their voice pitch when they speak. Even though experienced prevaricators work to control their voice when they talk, listeners can often discern their increase in voice pitch.

More Deliberate/Rapid Speech

Individuals who experience stress when they lie may speak more rapidly. On the other hand, persons who wish to have their misrepresentations completely heard may speak more slowly.